Lapping machine



W. S. PRAEG LAPPING MACHINE Jim-5, 1943.

Filed Aug. 1, 1941 ZKSheets-Sheet l W 09 w a My 3. l n 8 T m 0 ".LI/T M 7 En n 6 7 m... 6 E H I. a

INVENTOR. .PRQEZ ATTORNEYS BY W WALTER 25 Patented Jan. 5, 1943 LAPPING MACHINE Walter S. Praeg, Detroit, Mich,

tional Broach & Machine Company, Mich.-, a corporation of Michigan assignor to Na-. Detroit,

Application August 1, 1941, Serial No. 405,112

3 Claims.

The present invention relates to a gear finishing machine, and more particularly to a system of automatic controls therefor which insure stoppage of the machine at a particular point in the cycle.

Lapping machines for final finishing of gears are employed, in which the gear to be finished is run in mesh at limited crossed axes with a lapping tool in the form of a gear conjugate to the gear to be finished. In addition to the rotation of the gear and tool in mesh, a relative reciprocation is supplied between the gear and tool in a direction to distribute the finishing action of the lap from end to end of the gear teeth. This relative reciprocation may conveniently be provided by reciprocating the gear in a direction parallel to its axis. This reciprocation is carried out at a substantial speed for a substantial interval so that it is not feasible to provide automatic controls which will stop the machine after a predetermined number of reciprocations. According to the present invention. automatic timing mechanism is employed which causes reciprocation of the gear supporting mechanism in a direction parallel to the axis of the gear for a predetermined period of time, while the gear and tool are rotated in one direction. Following this, the rotation of the gear and tool is reversed and the reverse rotation is maintained for a second predetermined period'of time. The machine is then stopped by automatic controls;

If the gear being finished is a single gear, it is immaterial at which point during reciprocation of the gear that stoppage takes place. hand, if the gear being finished is a small gear of a cluster oi gears, it is very desirable that stoppage of the machine shall take place at a point in the traverse of the gear when the larger gear of the cluster is substantially removed from the lap.

According to prior practice, there was no control over the point in translation at which the machine stopped. The present invention provides simple and positive means for insuring the stoppage of the machine, which takes place when the gear is in a proper position for removal and replacement by a like gear.

It is accordingly an object of the present invention to provide an automatic interlock for a gear lapping machine which will insure stoppage of the machine at a predetermined point in the cycle.

It is a further object of the invention to provide a gear lapping machine in which automatic controls are provided, having timing means for- On the other determining the length of time of a lapping operation in conjunction with means for insurin stoppage of the machine at a predetermined point in the cycle.

Other objects of the invention will be apparent as the description proceeds and when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a schematic front elevation of the lapping machine to which the present invention is applied;

Figure 1A is a schematic end view;

Figure 2 is a simplified wiring diagram;

Figure 3 is a diagrammatic view of a timer employed; and

Figure 4 is a fragmentary side view looking to the left in Figure 3.

In Figure 1 I have shown a lapping machine comprising a base l0 and a column II. The base I0 is provided with a forwardly projecting knee on which is secured a support l2 for a lapping tool L, which is mounted for rotation. Column II is provided with a slide [3 adapted to be reciprocated in the direction of the arrow l4, and the slide l3 has supporting means l5 for a gear G to be worked upon, and this gear is indicated as a small gear of a cluster of gears having adjacent thereto a second larger gear G. Means are provided for rotating the lap L and the gears G and G in mesh, and may conveniently take the form of a reversing lap motor 20 connected to the. spindle of the lap L through suitable change gears. The detailed mechanism by which the motor rotates the lap L forms no part of the present invention and is accordingly not shown.

The slide l3 which carries the gears G and G is mounted for reciprocation in suitable ways provided in the column II and is preferably reciprocated by hydraulic means. These, means are not shown in Figure 1 but take the form of a suitable piston and cylinder indicated at 50 in Figure 2, interconnecting the column H and slide l3. Fluid is supplied under pressure to the piston and cylinder by means of a pump 2la which, according to the present invention is operated continuously from a motor 2|. In order to effect reversal of the slide [3 at predetermined points, a mechanical reversing valve 5! of conventional design is provided which is connected to an actuator 22 adapted to be tripped by adjustable dogs 23, 24 mounted on the slide l3.

Since the pump motor is operated continuously, the slide l3 will reciprocate continuously .so long as fluid is supplied under pressure to the reversing valve 5|. In order to interrupt reciprocation of slide I8, I provide a second solenoid control valve 52 in the hydraulic system which is adapted to vent the fluid supplied by the pump through a line 53 when solenoid 52a is deenergized. Since these valves may be conventional elements, they are indicated conventionally in Figure 2.

A limit switch LSI is carried. by the column II and is adapted to be tripped by an adjustable dog 25 carried by the slide l3. As shown in Figure 1, the slide I3 is at its extreme right-hand position, and it will be observed that the reversing valve controlled by the actuator 22 has just been tripped by the dog 24. This has occurred at a point in the reciprocation of the slide I3 when the large gear G is closest to the lap L. It is desired to prevent stoppage of the machine at this point in the cycle. It will be observed'that the dog 25 is at this time separated from the limit switch LSI. The dog 25 and the dog 23 are adjusted so that limit switch LSI is actuated at the same time as actuating mechanism 22 is tripped by the dog 23 to start reciprocation of the slide I3 to the right.

Referring now to the wiring diagram, I have shown the lap motor 28 which rotates the lap, and the pump motor 2i which operates pump 2 la to supply hydraulic fluid under pressure to the cylinder for reciprocating the slide I3, as connected across a three-wire circuit 30. The lap motor is adapted to be rotated in opposite directions, and for this purpose has feed and reverse relays F and R which are adapted to close normally open contacts Fa or Ra respectively. When neither the relay F nor R is energized, the lap motor is deenergized, since contacts Fa and Ra are normally open.

In the present wiring diagram, normally open contacts adapted to be closed by relays are indicated as parallel, spaced lines perpendicular to I the line wire.

The solenoid 52a is connected across two of the three wires leading to the pump motor, and is controlled by a pair of normally open contacts CRa which are closed when the relay OR is energized.

Connected across two of the three wires of the circuit 30 is a primary 3| of a transformer 32, the secondary 33 of which supplies current to the various control instrumentalities.

In the present circuit I employ two timers, which may be purchased in the open market and which are therefore shownonly diagrammatically in Figures '3 and 4. These timers are duplicates of each other as purchased but as employed in the circuits certain changes are made in the settings, as will hereinafter appear.

Referring now specifically to Figures 3 and 4, the timers comprise a frame 60 to which is pivoted, as indicated at El, a plate 62. "Plate 82, along its upper edge, has two rearwardly projecting ledges 33 and 64, whose extent is indicated in Figure 4. Displaced from the ledges 63 and 64 are two upstanding projections 85 and B6. Depending from the plate 62 is a lever 81 terminating in a tapped boss 68 in which is ment with the driving clutch plate II. On the threaded end of the shaft is a threaded member I8 having an upper U-shaped portion 11 which engages the frame as shown in Figure 3 and prevents rotation of the member I6 while permitting longitudinal displacement thereof by reason of the rotation of the threaded portion I4 and shaft I3. A torsion spring I8 is connected at one end to the shaft I3 and at the other end to the depending portion I2 of the frame 60. The torsion spring I8 is for the purpose of resetting the timer, which it does by reversing rotation of the shaft I3 after the same has been rotated to trip position by the motor M. This resetting occurs, of course, only after the clutch plates 'II and I5 have been disengaged.

The pivoted plate 62 has limited rocking motion between abutments 88 and 8| formed on the frame and is biased in a counterclockwise direction, as seen in Figure 3, by means of a tension spring 82. It will be apparent that, depending upon adjustment of the timing adjustment bolt '69, the plate 62 will be rocked in a clockwise direction as a result of engagement between the bolt 69 and the threaded member I5.

The frame 60 has upstanding arms 83 to which are pivoted a plurality of member's 84. Associated with each member 84 is a contact carrying arm 85. Members 84 and arms 85 are pivoted as indicated at 88 about the same axis. Intermediate each member 84 and its corresponding contact arm 85 is a compression spring 81 tending to rotate the contact carrying arm clockwise with respect to members 84. Each member 84 is provided with an abutment 38 and a removable pin 83. When the pin 89 is in position the contact arm 85 is rocked clockwise, as seen in Figure 3, into contact with the pin. If the pin is removed, the contact carrying arm is permitted to rock further in a clockwise direction. This permits use of the timers for various purposes, and by removal of the pin, one of the sets of contacts may be changed from normally open to normally closed, or vice versa.

A clutch solenoid C is provided, having a plunger 90 connected by means of a link 9| to a pin 92 which, in turn, connects the plunger 90 to all of the members 84. A bell crank 95 is pivoted to the frame 60, as indicated at 96, and is biased in a counterclockwise direction, as seen in Figure 3, by means of a compression spring 91. Compression spring 91, as will be seen in Figure 3, holds the plunger 90 upwardly except when the solenoid C is energized. A second lever 88 is pivoted to the frame 50, as indicated at '99, and has a clutch engaging portion I80 which engages the driven clutch plate I5. The bell crank 85 and lever 88 are interconnected by means of a link IIII. If desired, a spring may be provided, biasing the driven clutch plate I5 to the left.

As best seen in Figure 4, five contact carrying arms 85 are provided, and as shown in this figure three pairs of contacts Ga, Ma and Mb are thus provided for convenience. In Figure 4 the five contact carrying arms are designated 85a, 85b, 85c, 85d and 85a. As shown in Figures 3 and 4, the timer is completely deenergized and has been reset. It will be observed that the threaded member I6 has been moved to the right in this figure into contact with a shoulder Ila formed on the shaft I3.

plunger 88 is in uppermost position and is held there by reason of the compression spring 31. The contact carrying arms 85a to 85: inclusive are The solenoid C is deenergized and the H all in contact with their stops 88 or the pins 83 provided thereon. In the set-up as indicated in Figure 4 the pins 89 are all present so that the arms 85a to 85c inclusive all occupy the same plane.

If now a circuit is completed to the timer, thus energizing the timing motor M and the clutch solenoid C, the following takes place: The plunger 90 moves downwardly and rocks the bell crank 95 in a clockwise direction resulting in a corresponding rocking of the lever 98, thereby engaging clutch plates 1| and 15. The slow speed motor M is energized and rotation is thus imparted to the shaft 13. This rotation of the shaft 13 results in a slow feed of the threaded member 16 1 to the left, as seen in Figure 3, toward the timing adjusting bolt 69. Rotation of the threaded member is prevented by reason of engagement between its U-shaped portion 11 and the frame 60. At the same time downward movement of the plunger 90 rocks all of the members 84 in a clockwise direction an amount depending upon the amount of spacing provided between the head 90a of the plunger 90 and th frame of the clutch solenoid C. The amount of this rocking movement is, however, sufiicient so that the following changes take Place in the contacts Ca, Ma and Mb: The arm 85a moves downwardly until it engages the projection 65. downwardly farther than does the arm 85a and thereby closes the contacts Ca. moves downwardly. The arm 85d moves downwardly until it engages the projection 6-6. This prevents engagement with the contact carried by the arm 85c, and accordingly contacts Ma remain open. The arm 85c moves downwardly far-' ther than does the arm 85d, with the result that the contacts Mb are closed. Accordingly, upon energization of the timer the timing interval is started and contacts Ca and Mb are closed and contacts Ma remain open.

wardly under the influence of its compressionspring 81 while the arm 85b is prevented from such further downward movement by reason of its engagement with the ledge 63. This results in opening of contacts Ca. At the sam time the arm 85d moves farther downwardly by reason of the disengagement of the projection 66 from therebeneath. This results in closure of the contacts Ma and opening of the contacts Mb.

It will be observed that if, for example, the pin 89 were removed from the beneath the arm 85c, the contact Mb would be initially closed and would remain closed upon first energization of the timer. When the timer completed its timing interval and the plate 62 was moved, the contacts Mb would then open, as will later appear in the wiring diagram. The first timer to whose parts the numeral I is applied, is connected, as shown in Figure 2, to the second timer to whose parts the numeral 2 is applied, so that its contact Mb (the only one of its contacts which is employed) is normally closed and remains closed through the timing interval and is open only upon completion of the timing interval.

Attention is also drawn to the fact that the slow speed timing motor M is of the type which may be permitted to stall without injury thereto, and with the wiring diagram employd, this The arm 85b moves,

- shown in Figure 3 may continue to rotate and The arm 85c draws the threaded member 16 to the left until the plate 62 engages the stop on the abutment 80 provided on the frame 60. Continued energization oi the motor M results in no further operation, the motor merely stalling.

When the clutch solenoid C and the motor M are deenergized, the timer recycles. This takes place by reason of the torsion spring 18 which rotates the shaft 13 in the opposite direction from which it was previously driven by the motor M until the threaded member I6 engages the shoulder IIa previously referred to. At' the same time the plunger solenoid 90 moves 'upwardly, thus rocking members 84 counterclock wise to lift the contact arms 85 upwardly, and plate 62 resumes the position shown in Figure 3 by reason of the tension spring 82.

With the foregoing general remarks in mind, the control circuit comprises a secondary 33 which is connected to a relay P through overload switches indicated at 34. A normally closed switch 35 which is adapted to stop the pump motor, and a normally open switch 36 which is adapted to start the pump motor, complete the circuit through the pump relay P. A holding circuit including normally open contacts Pa adapted to be closed by energization of the relay, is provided in parallel aroundthe starting switch 36. Starting switch 36 is closed momentarily, which completes the circuit to .the relay P, thus closing normally open contacts Pa and establishing holding circuit 31, which maintains the relay P 'energized until the switch 35 is opened.

The relay P starts the pump motor 2| operating by closing normally open contact Pb, as will be readily apparent. At this time the solenoid 52 is deenergized, since normally open contacts CRa are open and, accordingly, the fluid supplied under pressure by the pump 2ia is vented, and the slide i3 is not caused to reciprocate.

Current is supplied to the control instrumentalities from line 40 through normally open contacts Pa, and include normally closed stop switch ll and a normally open start switch 42. When the start switch 42 is momentarily closed, a circuit is completed through line 43 to the relay CE. The relay CR, when energized, is adapted to close normally open contacts CRa, thus energizing the solenoid 52, and closes normally open contacts CRb, thus establishing a holding circuit around the start switch 42 through normally closed contact M211. The contact M2a is made normally closed by removing the pin 39 from beneath it s as seen in Figure 3. The start switch 42 is closed only momentarily, and then opens, and the circuits established remain complete through the contacts CRb, M2a and relay CR.

Closure of start switch 42, in addition to energizing the relay CR, also supplies current to both clutch solenoids Cl, C2, and to the motor MI through normally open, but now closed, contacts. Cla, which are closed by energization of the I clutch relay Cl.

As a result of energization of motor Mi, contacts Mia are closed and current is supplied through forward relay F, thus closing normally open contacts Fa, which energizes the lap motor 20 in a forward direction. A manual switch 45 permits reciprocation by pump 2! without rotation oflap L by motor 20.

A timing interval has now been established by energi'zation of motor MI and clutch relay Cl,

which continues for whatever period has been set on the timer when the timer trips, contact Mla opens and contact Mlb closes. Closure of contact Mlb establishes a circuit to the motor M2 and starts a timing interval controlled by the second timer, of which the motor M2 is a part. Closure of contacts Mlb also completes a circuit to the reverse relay R, thus closing reverse relay contacts Ra and reversing the lap motor 20. peration under these conditions continues until the second timer operates, at which time contacts M2a open. This leaves the relay CR and the reverse relay R energized through contacts CR1) and limit switch LSI.

As previously described, the limit switch LSI is adapted to be tripped after completion of each reciprocation of the slide l3. Accordingly, after the second timer has timed out its predetermined interval, operation of the machine continues until limit switch LSI is opened. Opening of the limit switch LSI breaks the circuit to the relay CR, and the solenoid 22 is thus deenergized by reason of the opening of the contacts CRa controlled by the relay CR. At the same time opening of the limit switch LSI breaks the circuit to the reverse relay R so that the lap motor 20 stops. The pump motor 2| continues to operate but the fluid pumped thereby is vented by reason of deenergization of solenoid 52a.

I have illustrated a simplified control system for obtaining the result sought and it will be un derstood that widely difierent specific control means may be employed to accomplish the result obtained by the present invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

l. A gear lapping machine comprising a frame, a rotary support on said frame, a slide on said frame, a second rotary support on said slide, said rotary supports being arranged to carry a meshed gear and gearlike lapping tool, a motor for rotating one of said supports, hydraulic means for reciprocating said slide, said hydraulic means comprising a piston and cylinder operatively connected between said frame and said slide, a pump for supplying fluid under pressure to said cylinder, a reversing valve actuated by motion of said slide for reversing the direction of application of pressure to said cylinder, a second valve for controlling the passage of fluid from said pump to said reversing valve, timing means for said motor and said hydraulic means effective to continue reciprocation of said slide for a predetermined time duration and to reverse said motor during said reciprocation, and control means effective upon termination of operation of said timing means to continue reciprocation of said slide until said gear and lapping tool reach a predetermined relative position, and to then actuate said second valve to interrupt the flow of fluid to said reversing valve to terminate reciprocation of said slide.

2. A gear lapping machine comprising a frame, a rotary support on said frame, a slide on said frame, a second rotary support on said slide, said rotary supports being arranged to carry a meshed gear and gearlike lapping tool, a reversible motor for rotating one of said supports, hydraulic means for reciprocating said slide, said hydraulic means comprising a piston and cylinder connect 'ed between said frame and said slide and a re versing valve actuated by motion of said slide for reversing the direction of application of fluid to said cylinder, a second valve for controlling the passage of fluid from said pump to said reversing valve, interlocked timing and control means, said timing means being effective to actuate said second valve to admit fluid to said reversing valve, to energize said reversible motor, to reverse said reversible motor after a predetermined time and then to transfer control of said motor and said second valve to said control' means, said control means being effective to thereafter continue energization of said motor and to continue actuation of said second valve to admit fluid to said reversing valve until said carriage is in a predetermined position, said controlmeans being then effective to interrupt the flow of fluid to said reversing valve to arrest reciprocation of said slide, and to deenergize said motor.

3. A gear lapping machine comprising a frame, a rotary support on said frame, a slide on said frame, a second rotary support on said slide, said rotary supports being arranged to carry a meshed gear and gearlike lapping tool, a reversible motor for rotating one of said supports, hydraulic means for reciprocating said slide, said hydraulic means comprising a piston and cylinder connected between said frame and said slide, a pump, a pump motor, means for supplying fluid under pressure from said pump to said cylinder comprising a reversing valve actuated by reciprocation of said slide, and a second valve controlling the application of pressure from said pump to said reversing valve, interlocked timing and control means, said timing means being effective to energize said reversible motor forwardly and reversely and to actuate said second valve to supply fluid to said reversing valve for a predetermined time duration, said control means being effective thereafter to continue energization of said reversible motor and actuation of said second valve until said slide has reached a predetermined point in its reciprocation and to then deenergize said motor and to actuate said second valve to interrupt the flow of fluid to said reversing valve,

WALTER S. PRAEG. 

